Systems and methods for controlling bi-directional forces for clot assessment

ABSTRACT

Systems and methods to analyze blood or other fluid sample. The systems and methods utilize bi-directional magnetic forces to push or pull a magnetic object along a post in a chamber housing the fluid sample both before and after clot initiation has been implicated. The magnetic object can be threadably connected to the post. In other embodiments, the chamber is configured such that the magnetic object does not rotate but only slides along the post. Once a clot has been detected, the washer can be moved either up or down to apply either compressive force or strain within the clot, as desired, to evaluate elastic properties or firmness of the clot.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional application of Ser. No. 16/110,179,filed Aug. 23, 2018, entitled, “SYSTEMS AND METHODS FOR CONTROLLINGBI-DIRECTIONAL FORCES FOR CLOT ASSESSMENT,” now allowed, which claimsthe benefit of the filing date of U.S. Provisional Patent ApplicationSer. No. 62/549,248, filed Aug. 23, 2017, entitled “SYSTEMS AND METHODSFOR CONTROLLING BI-DIRECTIONAL FORCES FOR CLOT ASSESSMENT,” the entireteachings of which are incorporated herein by reference.

BACKGROUND

The present disclosure relates to systems and methods of detecting andassessing changes in viscosity and viscoelasticity of a fluid sample(e.g., human blood) during a clot test.

The ability to detect changes in a property of a liquid that has beenplaced under the influence of a reagent that is capable of changing thatproperty has great practical value. Changes in viscosity, translucence,color, electrical conductivity, optical density, chemical componentconcentration, and many other properties have been used in a widevariety of tests. For example, detection of changes in the viscosity ofliquids such as blood, food products, and various other liquidcompositions (e.g., industrial fluids, oil well injection fluids, etc.)form the basis of many very practical tests.

Indeed, the ability to detect changes in the viscosity of human bloodcan even have life and death consequences. This follows from the factthat a proper balance between normal hemostasis and coagulation oranticoagulation is absolutely essential in maintaining the integrity ofthe human circulatory system—and in stopping both external and internalbleeding. It is, however, sometimes necessary to modify the naturalcoagulation system, either by increasing or decreasing the rate of bloodcoagulation. During open heart surgery for example, a patient is usuallysupported by a heart/lung bypass machine that provides extracorporealblood circulation while the heart is stopped. To prevent blood fromclotting upon exposure to the bypass system, the patient is treated withhigh doses of heparin, a naturally occurring substance thatsignificantly prolongs the clotting time of blood. When the time comesto remove the patient from the heart/lung bypass machine, however, it isdesirable for the patient's blood to regain its normal coagulationcharacteristics so that it will again be able to clot and assist inhealing incisions and stopping internal or external bleeding. Thisreversal of the effects of heparin is achieved by treating the patient'sblood with an anticoagulant-reversing substance (e.g., protamine)capable of neutralizing heparin or other anticoagulating substances.

To successfully maintain anticoagulation during a surgical procedure,and neutralize the heparin at the conclusion of surgery, it is highlydesirable to be able to quickly and accurately determine theconcentration of heparin in the patient's blood. Unfortunately, sincethe activity of heparin varies significantly from batch to batch, andfrom patient to patient, these determinations cannot be made simply onthe basis of the amount of heparin administered. Protamine also variesin potency from batch to batch and from patient to patient. Furthermore,protamine itself can act as an anticoagulant. Thus, for optimal reversalof a given heparin action, it is essential to use only that amount ofprotamine that will directly neutralize the amount of active heparin ina particular patient's blood.

Such reversals of a heparin action are detected by dose-response testswhich measure changes in blood clotting time in response to differingdoses of anticoagulant in order to determine the correct dose ofanticoagulant for a particular patient. Clotting time or activatedclotting time tests are used to determine whether a patient's blood hasachieved the desired level of anticoagulation. Heparin/protamine(anticoagulant/neutralizer) titration tests have been developed toprovide accurate determinations of heparin (anticoagulant) levels. Suchtests are based on measuring the time necessary for the blood tocoagulate. Consequently, these titration tests measure coagulation timeas an empirical measure of blood viscosity.

Optimal hemostasis management in cardiac surgery not only requirescareful dosing and monitoring of anticoagulant, such as heparin, it isalso important to monitor platelet function and other clotting factors,such as fibrinogen. Platelet dysfunction is believed to be the primarycause of excessive microvascular bleed following cardiopulmonary bypasssurgery. Activated platelet exert contractile force, when allowed tointeract with polymerizing fibrin, they significantly increase itstensile strength. While the measurement of clotting time can be achievedby measuring blood viscosity change, the measurement of blood clottensile strength change is best achieved by blood elasticity change.

By way of example only, U.S. Pat. No. 5,629,209 to Braun, Sr. et al.(“the '209 patent”) discloses apparatus and methods for detectingchanges in human blood viscosity through use of cartridges that, inconjunction with a test apparatus, are used to detect changes in bloodviscosity. Heparinized blood is introduced into the cartridge through aninjection port and fills the blood receiving/dispensing reservoir. Theblood then moves from the reservoir through at least one conduit into atleast one blood-receiving test chamber where it is subjected to aviscosity test. In this test, a freely movable ferromagnetic object isplaced within the blood-receiving test chamber. The ferromagnetic objectis moved up by an electromagnet in the test apparatus and falls viagravitational pull. Changes in the viscosity of the blood through whichthe ferromagnetic object falls are detected by determining the positionof the ferromagnetic object in the blood-receiving test chamber over agiven time period or a given number of rises and falls of theferromagnetic object. The incoming blood sample can be mixed with ablood viscosity altering agent (e.g., protamine) as it passes throughthe conduit to the blood-receiving test chamber. Any air in the fluidcommunication system in front of the incoming blood sample is ventedthrough an air vent/fluid plug device. In addition, U.S. Pat. No.6,613,286 to Braun, Sr. et al. discloses a related apparatus havingconstructed passages for increasing the velocity of the fluid flowthough said constricted passage and thereby more thoroughly mixing theliquid (blood) and a reagent.

The present disclosure provides improvements generally related to theabove.

SUMMARY

Systems and methods of the present disclosure can be used in virtuallyany test where a reagent is mixed with a liquid sample and then testedfor some change in a property of the resulting liquid/reagent mixture.Disclosed systems and methods are particularly well suited for clottingtime tests, dose-response tests, and especially titration tests on humanblood taken from patients undergoing anticoagulation therapy duringheart/lung bypass surgery.

One example of a test procedure commences when a liquid sample to betested is introduced, under pressure, into a cartridge containing one ormore test chambers in which a low-carbon ferromagnetic washer ispositioned over a post for mixing test samples and assay reagent andalso for sensing the blood viscoelasticity change during the clottingprocess. Clot detection can be accomplished, for example, by insertingthe cartridge into a device and assessing a viscosity change of thesample through lifting of the washer via magnetic lifting force anddropping of the washer and allowing it to fall via gravity. There aresome drawbacks, however, to devices that are only capable of activelylifting the washer.

During a test, blood clots can form at any location between a floor anda ceiling of a test chamber. When a clot forms above the washer, thewasher can be actively moved up using the device described above byapplying the magnetic lifting force to apply compression. It is noted,however, that since the magnetic force is dependent on the gap betweenthe magnet and the washer, and greater lifting force is applied tocompress the clot between the washer and the test chamber top andstretch the clot between the washer and the bottom of the test chamberwhen the washer is closer to the magnet that, therefore, the stressforce in a strain-stress elasticity measurement of the clot in thismethod is not controlled. The strain (compression or stretching) of theclot is not controlled either because the washer initial location at thetime of clot formation is not controlled, the distance the washer to bemoved up is not controlled. Because neither strain nor stress forces arecontrolled in the system, the elasticity of the blood clot cannot bereproducibly measured. In the case of a clot formed under the washer,the passive gravity force of the washer on top of the clot would notallow the washer to drop further until the clot starts to retract, whichdoes not occur until later (typically at least about 15 minutes afterinitiation of the clot test) in the blood hemostasis process. In view ofthe above, the present inventors recognized that in order for a plateletfunction test to be able to assess platelet strength and function viaclot elasticity measurements, it is desirable for a test device ormachine of the system to be able to measure clot elasticity withcontrolled stress force or strain distance and that actively controlledbi-directional forces can achieve controlled strain and stress forcesapplied to the clot. The bi-directional forces on a washer can beprovided, for example, by utilizing a magnetic washer that can becontrolled with an actuating magnet in two directions, by selectivelyaligning the poles of the magnetic washer with the poles of theactuating magnet to either push or pull the magnetic washer along thepost. The position of the washer can be measured with a position sensor.In this way, stress or strain can be applied to the clot for use inmeasuring viscoelasticity of the clot. In one embodiment, the actuatingmagnet is a horseshoe magnet that can rotate about its center axis toapply bi-directional forces to the magnetic washer. Similarly, in otherembodiments, the actuating magnet is an electromagnet and the polarityof the electromagnet can change as the current reverses direction everyhalf cycle (AC voltage or current source) to apply bi-directional forcesto the magnetic washer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a cartridge and a test machine in whichthe cartridge is inserted.

FIG. 2 is a top view of a cartridge made according to certainembodiments of this disclosure.

FIG. 3 is a perspective, exploded, view of the cartridge shown in FIG.2.

FIG. 3A is a perspective, exploded, view of the cartridge of FIG. 3about to be provided with a flexible top.

FIG. 4 is a side view of the cartridge shown in FIG. 2.

FIG. 5 is a side view of the cartridge shown in FIG. 2 with a syringeattached to the cartridge.

FIG. 6 is a top view of another embodiment of the cartridges of thepresent disclosure.

FIG. 7 is a perspective, exploded view of the cartridge shown in FIG. 6.

FIG. 8 is a rear view of the cartridge shown in FIG. 6.

FIG. 9 is an enlarged top view of a fluid entry conduit, fluid-receivingtest chamber, fluid exit conduit and vent/fluid plug device of thepresent disclosure.

FIG. 10 is an enlarged top view of another fluid entry conduit,fluid-receiving test chamber, fluid exit conduit and vent/fluid plugdevice of the present disclosure.

FIG. 10A is an enlarged top view of another cartridge; wherein theconduit between the fluid receiving/dispensing reservoir and thefluid-receiving test chamber has a constricted region that angles fromthe first part of the conduit and approaches the wall of fluid-receivingtest chamber in a tangential manner.

FIG. 11 is a top view of another cartridge.

FIG. 12 is a rear view of the cartridge shown in FIG. 11.

FIG. 13 is a bottom view of the cartridge shown in FIG. 11.

FIG. 14 is an enlarged, cut-away, cross-sectional view of the cartridgeshown in FIG. 11 being used in conjunction with a syringe,

FIG. 15 is a partial, schematic illustration of another embodiment of acartridge including at least one test chamber having a threaded guidepost that can be engaged with a threaded magnetic washer.

FIG. 16A is a partial, schematic illustration of a system including thecartridge of FIG. 15 (only part of which is shown) including a machinehaving an actuating magnet that is oriented to pull the washer in adirection of the actuating magnet.

FIG. 16B is a partial, schematic illustration of the system of FIG. 16Aillustrating the actuating magnet positioned to push the washer in adirection away from the actuating magnet.

FIG. 17A is a partial, schematic illustration of the actuating magnet ofFIGS. 16A-16B oriented to push the washer toward a floor of the testchamber to compress a clot formed below the washer (the non-clottedportion of the fluid sample is not shown for clarity).

FIG. 17B is a partial, schematic illustration of the actuating magnet ofFIGS. 16A-16B oriented to pull the washer toward a ceiling of the testchamber to compress a clot formed above the washer (the non-clottedportion of the fluid sample is not shown for clarity).

FIG. 17C is a partial, schematic illustration of the actuating magnet ofFIGS. 16A-16C oriented to push the washer toward the floor of the testchamber to stretch a clot formed within the washer (the non-clottedportion of the fluid sample is not shown for clarity).

FIG. 18A is a partial, schematic cross-sectional view of an alternateembodiment including a test chamber having a magnetic washer positionedover a guide post.

FIG. 18B is a top view of the test chamber of FIG. 17A.

FIG. 19A is a partial, schematic illustration of a system including acartridge (only, part of which is shown) including one or more testchambers of the type of FIGS. 17A-17B showing the actuating magnetpositioned to push the washer in a direction away from the actuatingmagnet.

FIG. 19B is a partial, schematic illustration of the system of FIG. 18Aillustrating the actuating magnet positioned to pull the washer in adirection toward the actuating magnet.

DETAILED DESCRIPTION

By way of background, FIG. 1 depicts one example of a disposablecartridge 10 conceptually associated with a machine 12 for testing someproperty of a liquid that is mixed with a reagent. The machine 12 can beprovided with one or more sensor devices (known to those skilled in thetest machine manufacturing arts), for detecting various properties of agiven liquid/reagent sample. For example, the one or more sensingdevices can be used to detect the viscosity, translucence, color,optical density, electrical conductivity, magnetic properties, fluidcomponent concentrations, electromagnetic response, etc. of a sample (oran object placed in the sample e.g., the ferromagnetic washer shown inFIGS. 9, 10 and 14). That is to say that in some of the exampleembodiments of this disclosure, the machine 12 will be provided withmore than one kind of sensing devices so that the machine 12 cansimultaneously (or sequentially) detect more than one property of thesample being tested. Such a machine 12 will generally comprises a base14 and an upper portion 16. The upper portion 16 can include a displaydevice 18 (including a touch-sensitive display screen) such as thatdepicted in FIG. 1. Contained within the base 14 of the machine 12 is acartridge holder mechanism (not shown). The cartridge 10 is insertedinto the cartridge holder mechanism via a slot 20 that is optionallylocated in the front of the base 14.

By the nature of the test(s) as it (they) may, the cartridge 10 may beinserted into the machine 12 before or after said cartridge 10 is filledwith a liquid sample to be tested. FIG. 1 also depicts a syringe 22 usedto fill the cartridge 10 with a liquid to be tested. In someembodiments, the syringe 22 is used to fill the cartridge 10 with theliquid sample after the cartridge is inserted into the slot 20 in thebase 14. Thereafter, the syringe 22 remains attached to the cartridge 10in the manner suggested in FIG. 1. So attached, the syringe 22 canconveniently serve as a “handle” for the cartridge 10. Thissyringe/handle feature is very useful in performing the manualoperations associated with placing the cartridge 10 in the cartridgereceiving slot 20 and subsequently removing the cartridge 10 from saidslot. The cartridge and its syringe/handle can be disposed of as a unit.This feature serves to protect the machine operator from inadvertentcontact with the liquid being tested.

After a cartridge 10 containing a liquid sample is placed in the slot20, the machine 12 conducts an analytical test following somepredetermined procedure in accordance with the type of test desired.Such procedures are known to those skilled in the manufacture of testmachines. These test results also may be compared (for example, throughcomputer-programmed comparisons) with other programmed test informationand/or with other test results. For example, the detailed testprocedures taught in the U.S. Pat. No. 5,629,209 (Braun, Sr., et al.),the disclosure of which is hereby incorporated by reference in itsentirety, can be carried out. Again, the machine 12 can display theresults of the test on a display screen 18.

FIG. 2 shows a top view of one embodiment of a cartridge 10 such as thatdepicted in FIG. 1. The cartridge 10 is substantially planar and formedof a strong, rigid material (for example, a plastic or acrylic) that isinert with respect to the liquid/reagent sample being tested. The rigidmaterial from which the cartridge 10 is formed may be partially orwholly transparent. The cartridge 10 may be manufactured as a unitary ormonolithic piece (for example, by injection molding techniques), or itmay be assembled from various separate parts. In one manufacturingmethod (see FIG. 3), a separate and distinct cartridge top 10(T) isattached on a cartridge bottom 10(B) after a liquid sample alteringreagent (e.g., a blood viscosity-altering reagent) is placed in aconduit (e.g., conduit 30A) in the cartridge bottom 10(B). In someembodiments, the cartridge top 10(T) will be a flexible material that isused to cover the top of the fluid communication system and thereby formthe top of the cartridge. This flexible material can be a polymer based,paper based material. In either case the material should be imperviousto the liquid sample. In other embodiments, this flexible material willhave a label-like quality in that select portions of its underside areprovided with an adhesive material. The top side of this label couldhave printed material such as directions for using the cartridge, barcodes, words of caution, and/or technical specifications, etc. Infurther embodiments, the top of the cartridge will be a stiff,transparent, plastic material such as Mylar® BoPET (biaxially-orientedpolyethylene terephthalate). It is to be understood, however, thatvarious other types of plastic materials may be used for such tops 10(T)so long as they provide a fluid-impervious seal between the top 10(T)and the cartridge bottom 10(B). The cartridge bottom 10(B) can be madeof compatible plastic materials that are capable of being held in anabutting relationship by a glue or adhesive material.

As shown in FIG. 2, the cartridge 10 is provided with an injection port24 (e.g., a luer lock) that is located in a nominal rear portion 26 ofthe cartridge 10. A liquid sample is introduced into the cartridge 10through this injection port 24. The injected liquid may already havebeen mixed with a reagent before it enters the cartridge. In certainembodiments, however, the mixing of the liquid and reagent takes placeinside the cartridge 10. In any case, the injection port 24 directs theliquid sample into a fluid receiving/dispensing reservoir 28. From thefluid receiving/dispensing reservoir 28, the liquid sample proceedsthrough one or more fluid inlet conduits 30A, 30B, 30C . . . 30F, etc.Each such conduit respectively leads to a fluid-receiving test chamber32A, 32B, 32C . . . 32F, etc., each having a guide post 48A, 48B, 48C .. . 48F, etc. In some embodiments, the fluid conduits have a narrowregion to reduce blood flow speed, which can cause air entrapment in thefluid-receiving test chamber 32A, 32B, 32C . . . 32F, etc. The motiveforce for this movement of the subject liquid (e.g., blood) through thecartridge 10 is provided by a fluid injection or pumping mechanism. Amanually operated syringe such as the syringe 22 shown in FIG. 1 can beused for pumping the liquid sample through the cartridge 10. In someembodiments, the conduits 30A, 30B . . . 30F are provided with aconstricted portions 30A(1), 30B(1) . . . 30F(1) that angle from adirection that generally leads toward the center of the respectivefluid-receiving test chambers 32A, 32B . . . 32F, to their respectivewall regions.

Each fluid-receiving test chamber 32A, 32B, 32C, etc. may be equidistantfrom the fluid receiving/dispensing reservoir 28. Consequently theliquid sample moves from the fluid receiving/dispensing reservoir 28simultaneously, or nearly so, into each fluid-receiving test chamber32A, 32B, 32C, etc. In those embodiments in which the liquid samplebeing tested is human blood, each fluid-receiving test chamber 32A, 32B,32C, etc. can have a volume of about 100 μl to about 250 μl. Althoughsix fluid-receiving test chambers 32A, 32B, 32C, etc. are shown in FIG.2, it should be understood that any desired number of fluid-receivingtest chambers can be formed in the cartridge 10. Indeed, suitablecartridges could contain only one such fluid-receiving test chamber.

Again, in various embodiments, multiple fluid-receiving test chambers32A, 32B, 32C, etc. will be filled nearly simultaneously in order toenhance the accuracy of the analytical test results. To achieve thisnear-simultaneous filling, the fluid receiving/dispensing reservoir 28can be provided with a substantially semicircular configuration so that,upon being filled, it acts as a manifold that tends to uniformly deliverthe liquid sample to the fluid-receiving test chambers 32A, 32B, 32C,etc. As seen in FIGS. 3, 4 and 5, the injection port 24 enters the top10(T) and rear 26 of the cartridge 10. It is then pressured (e.g., by asyringe) into the fluid receiving/dispensing reservoir 28. As can bebetter seen in FIG. 14, the conduits 30A, 30B, 30C, etc. can optionallybe arrayed along the front end 34 of the fluid receiving/dispensingreservoir 28. The conduits 30A, 30B, 30C, etc. can be located closer tothe top of the fluid receiving/dispensing reservoir 28 relative tolocation of the fluid inlet leading into the fluid receiving/dispensingtest chamber 28 from the injection port 24. Thus, a fluid sample canenter a lower part of one end of the fluid receiving/dispensingreservoir 28, substantially fills the fluid receiving/dispensingreservoir 28 and then leaves said chamber 28 at a relatively higherlevel of the fluid receiving/dispensing reservoir 28.

Any air contained in the cartridge 10 must be vented as the liquidsample is pumped into said cartridge. To this end, each fluid receivingtest chamber 32A, 32B, 32C, etc. is provided with a second conduit 36A,36B, 36C, etc. (“fluid exit conduits”) that lead from a givenfluid-receiving test chamber 32A, 32B, 32C, etc. to a given airvent/fluid plug device 38A, 38B, 38C, etc. Such a vent/fluid plug isdetailed in FIGS. 9 and 10. As the liquid sample enters the cartridge 10and moves into the fluid receiving/dispensing chamber 28, air containedin the conduits 30A, 30B, 30C, etc., the fluid receiving/dispensingreservoir 28, fluid-receiving test chambers 32A, 32B, 32C, etc., thefluid exit conduits 36A, 36B, 36C, etc. and the vent/fluid plug devices38A, 38B, 38C, etc. is driven before the incoming fluid and vented outof the cartridge 10. In some embodiments, this venting will be donethrough the bottom side 40 of the cartridge 10 (see FIGS. 13 and 14) viaair vent/fluid plug device 38. This venting also could be done throughthe top 10(T) or side(s) 42 of the cartridge 10 as well. The exitconduits 36A, 36B, 36C, etc. can exit their respective fluid receivingchambers 32A, 32B, etc. at a position that is substantially opposite theposition where the fluid inlet conduits 30A, 30B, etc. enter theirrespective fluid-receiving test chambers 32A, 32B, etc.

When the incoming liquid reaches the air vent/fluid plug device 38, apermanent liquid lock is formed. This prevents any further motion ofliquid through the cartridge 10. In other words, the air vent/fluid plugdevice 38 allows air displaced by incoming liquid to exit the cartridge10, but prevents liquid from leaving the cartridge 10 via said airvent/fluid plug device 38. In one embodiment, the air vent/fluid plugdevice 38 is formed of Porex® plastic (Porex Corp. no. X6870). Thismaterial is porous to a gas such as air, but is not porous to a liquidsuch as blood, and therefore acts as a liquid lock. The fluidcommunication system created by the fluid receiving/dispensing reservoir28, conduit(s) 30A, 30B, etc., fluid-receiving test chamber(s) 32A, 32B,etc., and air vent/fluid plug device(s) 38A, 38B, etc. automaticallyplaces the correct amount of liquid in each fluid-receiving test chamber32A, 32B, etc. Hence, no liquid volume measurements need to be made byhuman operators. This automatic measuring action provides a meanswhereby the volume of the fluid samples will not vary between therespective fluid-receiving chambers 32, or between tests. Fail-safeprovisions also may be provided by the machine 12 to disclose incompletefilling of any fluid-receiving test chamber 32A, 32B, etc.

FIG. 3 is an exploded perspective view of the cartridge 10 shown in FIG.3. In this disassembled state a reagent can be readily placed in one ormore of the conduits (e.g., conduit 30A). In some embodiments of thisdisclosure, the reagent will be placed in conduit in the form of asolution or suspension. The carrier (water, alcohol, etc.) for thereagent will then be evaporated and thereby leaving behind a dried formof the reagent. The cartridge top 10(T) then can be placed on thecartridge bottom 10(B) e.g., by gluing, by an adhesive placed on theunderside of a flexible, label-like cartridge top 10(T), and therebyform the unified cartridge 10 shown in FIGS. 1 and 2.

FIG. 3A is an alternative embodiment wherein a top 10(T)(F) for thecartridge bottom 10(B) is made of a flexible material whose left end isshown curled away from a flat configuration. The underside 43 of the top10(T)(F) is provided with regions having an adhesive material 45. Theadhesive material 45 is, can be absent from those areas that cover thefluid receiving test chambers 32A . . . 32F, i.e., those round areas onthe underside 43 of the top 10(T)(F) designated as 32A(A) . . . 32F(A).

FIG. 4 is a side view of the cartridge 10 shown in FIG. 2. Itparticularly illustrates how the injection port 24 is mounted to the top10(T) and/or rear end 26 of the cartridge 10 at an angle beta. Thisangle beta can optionally be from about 30° to about 45°.

FIG. 5 is a partially cut away side view of the cartridge 10 shown inFIG. 2 having a syringe connected to the injection port 24. The syringe22 can be used as a handle for the cartridge 10. This cut away view alsosuggests that a threaded nose 25 of the syringe can be threaded into athreaded injection port 24.

FIG. 6 depicts another embodiment wherein a cartridge 10(C) is providedwith six fluid receiving test chambers.

FIG. 7 is an exploded view of the cartridge shown in FIG. 6.

FIG. 8 is a rear view of the cartridge 10(A) shown in FIG. 6.

FIG. 9 is an enlarged top view of a fluid-receiving test chamber 32 andthe fluid inlet conduit 30, fluid exit conduit 36 and air vent/fluidplug 38 associated with it. It also illustrates use of the disclosedembodiments in a test wherein: movement of a ferromagnetic washer-likeobject 46 positioned around one respective guide post 48 of the testchamber 32 is used to detect changes in a property of the sample (e.g.,the viscosity of the blood sample). In such a test, at least one, and insome embodiments each, fluid-receiving test chamber will contain such afreely movable ferromagnetic object such as the washer-like object 46depicted in FIGS. 9, 10 and 14. When a blood viscosity analysis isperformed, the ferromagnetic object 46 is raised under a magnetic actionto the top of the test chamber and then is permitted to fall through theblood/reagent mixture to the bottom of the test chamber. One or morecharacteristics of the descent of the washer (e.g., descent time) canmeasured by detecting the position of the ferromagnetic object undervarious conditions (e.g., after repeated raising and lowering of thewasher). This reciprocating motion of the ferromagnetic object isrepeated until a change in fall time in one or more of thefluid-receiving test chambers signals a change in the viscosity of theblood/reagent mixture within those one or more fluid-receiving testchambers. FIG. 9 also shows that the fluid-receiving test chamber 32 canbe configured to have a round external wall 44. As can be better seen inFIG. 14, the washer-like object 46 is free to vertically rise and fallinside the test chamber 32. This vertical rise and fall may be guided bya guide post 48 in the test chamber. In effect a guide post 48 mayoccupy the washer-like object's center hole 50.

FIG. 9 also depicts a fluid sample 52 being pumped into thefluid-receiving test chamber 32 via conduit 30. The conduit 30 is shownprovided with a constricted passage 54. A reagent 56 (e.g., a driedblood viscosity changing reagent) is shown positioned in a center regionof said constricted passage 54. In this view, the constricted passageflares out into a conduit section 30′ having a cross section comparableto the fluid inlet conduit 30 before leading into the fluid-receivingtest chamber 32. In FIG. 9, conduit 30 is shown positioned in analternate orientation with respect to the fluid-receiving test chamber32. That is to say that, in effect, the flow 52 of the fluid sample isaimed at the center 58 of the fluid-receiving test chamber 32. Fluidflow 52′ from the fluid-receiving test chamber 32 exits said testchamber, via fluid exit conduit 36, in a similar manner. That is to saythat the exit flow 52′ of the fluid is through an exit conduit 36 thatis essentially perpendicular to the chamber wall 44 (i.e., the fluidflow 52′ from the test chamber 32 can be thought of as emanating from aregion near the center 58 of said test chamber). The exit conduit 36leads to an air vent/fluid plug device 38.

FIG. 10 shows yet another embodiment wherein the inlet conduit 30 has aconstricted passage 54 (containing a reagent 56) that leads into thefluid-receiving test chamber 32 in a substantially tangential flowpattern. That is to say that the flow of fluid 52 into thefluid-receiving test chamber 32 is directed more toward the outer wall44 of the test chamber rather than toward the chamber's center 58 (as itis in the embodiment shown in FIG. 9). This substantially tangentialflow pattern is depicted in FIG. 10 by first placing a tangent line60/60′ on the chamber wall 44 such that it is substantiallyperpendicular to the round chamber's center line 62/62′. The angle thetaat which the constricted passage 54 approaches the wall 44 of thefluid-receiving test chamber 32 can be less than 45°. In someembodiments, the angle theta will be less than 20°; and in someembodiments this angle theta will approach the zero angle associatedwith tangent line 60/60′.

FIG. 10A shows another embodiment wherein the inlet conduit 30 has aconstricted passage 54 (containing a reagent 56) that leads into thefluid-receiving test chamber 32 in a substantially tangential flowpattern. The flow 52 through a first portion of the conduit 30 isgenerally aimed toward the center 58 of the fluid-receiving test chamber32. This flow 52 is however directed into a constricted passage 54 at anangle Beta prime which is such that the flow 52 enters thefluid-receiving test chamber 32 in a tangential fashion (as opposed tobeing aimed at the center 58 of the fluid-receiving test chamber 32),near the perimeter or outer wall 44 of said test chamber 32. That is tosay that the flow of fluid 52 into the fluid-receiving test chamber 32is directed more toward the outer wall 44 of the test chamber ratherthan toward the chamber's center 58 (as it is in the embodiment shown inFIG. 9). This substantially tangential flow pattern is depicted in FIG.10A by first placing a tangent line 60/60′ on the chamber wall 44 suchthat it is substantially perpendicular to the round chamber's centerline 62/62′. The angle Beta prime at which the constricted passage 54approaches the wall 44 of the fluid-receiving test chamber 32 can beless than 45°. In some embodiments, the angle Beta prime will be lessthan 20°; and in further embodiments this angle Beta prime will approachthe zero angle associated with tangent line 60/60′.

Similarly, fluid flow 52′ out of the test chamber 32 leaves in atangential flow direction as well. This circumstance is depicted in FIG.10A by virtue of the fact that the fluid flow 52′ out of the testchamber 32 follows a direction that does not pass through the center 58of the chamber, but rather is more tangent to the round outer wall 44 ofsaid test chamber 32. This substantially tangential flow pattern isdepicted in FIG. 10A by placing a tangent line 64/64′ on the chamberwall 44 such that it is substantially perpendicular to the chamber'scenter line 62/62′. The angle gamma at which the exit conduit 36 leavesthe wall 44 of the fluid-receiving test chamber 32 is can be less than45°. In some embodiments, the angle gamma will be less than 20°; and inother embodiments this angle gamma will approach the zero angleassociated with the tangent line 64/64′.

FIG. 11 shows a top view of another cartridge 10(B) constructedaccording to the teachings of this patent disclosure. In thisembodiment, the inlet conduits 30A, 30B, 30C . . . 30F are eachrespectively aimed at a center of a fluid-receiving test chamber 32A,32B, 32C, etc. while the exit conduits 36A, 36B, 36C, etc. leave saidtest chambers in a tangential direction.

FIG. 12 is an end view of the cartridge 10(B) shown in FIG. 11. Itparticularly illustrates one embodiment of the present disclosure whensuch a cartridge is made in two layers 10(B) and 10(T).

FIG. 13 is a bottom view of the cartridge 10(B) shown in FIG. 11. Itillustrates one embodiment wherein the air vent/fluid plug devices 38lead to the bottom side 40 of the cartridge 10(B).

FIG. 14 is an enlarged cross sectional view of the cartridge 10(B) shownin FIG. 11 as seen along section line 14-14 thereof. A syringe 22 isdepicted as being threaded into an injection port 24 in the cartridge10(B). It could be compression fitted as well. Such a compression fitalso could be augmented by use of a locking device that mechanicallyconnects the syringe 22 to the injection port 24. For example, thelocking device may be a so-called “bayonet lock” wherein a nub or otherprotrusion on the syringe 22 may be guided into a first keyway. Uponreaching the bottom end of such a first keyway, the syringe 22 isrotated (about 90°) and thereby forcing the protrusion into a secondreceiver slot or keyway that is substantially perpendicular to the pathof the first keyway.

Fluid flow 52 from the syringe 22 enters the injection port 24 and flowsunder pressure provided by the syringe 22 to the fluidreceiving/dispensing chamber 28. In this embodiment, the fluid flow 52will enter said chamber 28 at a level that is lower than the level atwhich fluid leaves said chamber 28 (i.e., at the level of conduit 30A).Fluid leaving chamber 28 enters inlet conduit 30A and flows to afluid-receiving test chamber 32. In one embodiment, the inlet conduit30A has a constricted passage 54 (see again FIG. 10). Optionally, thereagent 56 that the liquid will be mixed with is positioned in thisconstricted passage 54. Dried deposits of such reagents 56 areparticularly beneficial in this particular location. Upon leaving theinlet conduit 30A (or its constricted passage 54) the liquid flow entersthe fluid-receiving test chamber 32A. After said test chamber 32A issubstantially filled, the liquid flow enters the fluid exit conduit 36that leads to the air vent/fluid plug device 38. Again, this deviceallows air to be driven from the cartridge 10B, but prevents the liquidfrom leaving said cartridge via the air vent/fluid plug 38.

FIG. 14 also illustrates examples of how two distinct kinds of tests canbe conducted in the cartridges of this patent disclosure. The first typeof test is depicted by the penetration of a wave-like line 68 into thetest chamber 32. This wave-like line is intended to depictelectromagnetic energy of various kinds. Such energy can be used todetect various attributes of a liquid residing in the test chamber 32.Again a wide variety of tests for viscosity, translucence, color,electrical conductivity, optical density, chemical componentconcentration, etc. can be conducted by exposing the sample to variousforms of electromagnetic energy. One or more different forms ofelectromagnetic energy 68 can be produced by a test machine such as thetest machine 12 depicted in FIG. 1. One or more different forms ofelectromagnetic energy also can be directed at one or more test chambers32A, 32B, 32C, etc. in a cartridge. They also can be directed atdifferent chambers simultaneously, or they can be directed at the sametest chamber (e.g., the test chamber 32A of FIG. 14) sequentially.

Again, one type of test in the practice of this disclosure involvesdetection of the portion of a ferromagnetic washer 46 such as that shownin FIGS. 9 and 10. Again, movement of such a washer 46 through a liquidwhose viscosity changes (as a result of contact with a viscosityaltering reagent) can form the basis of various tests. Once again,applicants will use movement of such a washer 46 through a blood sampleas a representative use of the cartridges of this patent disclosure. Insuch a test, a ferromagnetic object (such as one made of iron, nickel,cobalt, and numerous alloys known to the art) can be placed in at leastone of several fluid-receiving test chambers 32A, 32B, 32C, etc., in agiven cartridge. Such a ferromagnetic object may act both to induce andto measure viscosity changes in the fluid. In one embodiment, thisferromagnetic object is a single piece such as a washer made of steel orother iron-based alloy. Such a washer is depicted in FIGS. 9 and 10. Toensure accurate and reliable results of the analytical tests, each suchwasher 46 should meet strict specifications, especially as to itsphysical measurements. Although the ferromagnetic object 46 used in thisembodiment will normally be a steel or other iron-based alloy washer, itshould be understood that other magnetically affected materials, havingother physical shapes, are within the scope of the present disclosure.Hence, references herein to “washers” may include other materials andshapes. Indeed, ferromagnetic objects can be introduced to in liquidsample in the form of beads, large particles, or even filings. Theessential attribute is that the ferromagnetic object be freely movablein the fluid within the fluid-receiving test chamber 32. Such aferromagnetic object can be moved under the action of a magnet or byother means, for example, by the force of gravity. In any case, theferromagnetic object can be configured not have a large volume relativeto the volume of the fluid-receiving test chamber 38. In the context ofblood testing, applicants have found that if a ferromagnetic washer 46is employed, it can be configured to displace a volume of about 10 μl toabout 50 Thus, the volume of the liquid sample that can be injected intoa given fluid-receiving test chamber 32 can be about 50 μl to about 240μl, based on a total fluid test chamber volume of about 100 μl to about250 μl. As was previously noted, one embodiment of this disclosureemploys a ferromagnetic washer 46 having a center hole in which a guidepost 48 is positioned to guide the washer substantially straight up andstraight down in the test chamber 32.

In a blood viscosity test, a viscosity-altering reagent can be placedwithin the cartridge between the injection port 24 and thefluid-receiving test chamber 32 (e.g., in the injection port itself, inthe fluid receiving/dispensing reservoir or in a conduit that connectsthe fluid receiving/dispensing channel). Again, one desired location isin a constricted passage of a conduit located between the fluidreceiving/dispensing reservoir and the fluid receiving test chamber. Inthe case of a heparin/protamine test, for example, a different amount ofprotamine, which is a heparin neutralizer, can be placed within aconstricted passage of each of several conduits before a heparinizedblood sample is introduced into the cartridge. The blood mixes with theprotamine as it travels through a given conduit system. After the bloodfills the fluid receiving test chamber(s), the test apparatus proceedsto raise the ferromagnetic object in one or more of the fluid-receivingtest chambers and then repeatedly measures one or more fallcharacteristics (e.g., changes in fall times) of that ferromagneticobject through the blood sample. Useful inferences are then made fromsuch fall times (relative to some standard and/or relative to fall timesin different test chambers within the system). For example, the testchamber in which blood clots first is the test chamber in which theprotamine level is closest to the heparin level of the blood sample.

It also should be understood that different amounts or more than onetype of viscosity-altering substance may be used in each conduit 30A,30B, 30C, etc. For example, in a heparin/protamine test of human blood,each such conduit may receive a different amount of protamine and, ifdesired, one or more different viscosity-altering substances (forexample, a clotting activator such as tissue thromboplastin) in additionto the protamine. Those skilled in this art also will appreciate thatseveral viscosity-altering substances can serve to decrease the tendencyof blood to coagulate. They include, but are not limited to, heparin,warfarin, dicumarol, acenocoumarol, phenprocoumon, diphenadione,phenindione, sodium citrate, citric acid, citrate dextrose, citratephosphate dextrose, aspirin, and edetate disodium. Viscosity-alteringsubstances that act to increase the tendency of blood to coagulateinclude, but are not limited to, protamine, platelet-activating factor,factor VIII, factor IX complex, factor XVII, fibrinogen, aminocaproicacid, thrombin, thromboplastin, vitamin K, calcium chloride, kaolin, anddiatomaceous earth.

As an example of such usage for a heparin/protamine test, in which thefluid sample to be analyzed is heparinized human blood, theviscosity-altering substance 56 will be protamine. A certain amount ofprotamine will neutralize the activity of an equivalent amount ofheparin, thereby permitting the heparinized blood to clot. Thus, toprepare a cartridge 10 for a heparin/protamine test, a different amountof protamine can be placed in each of the conduits 30A, 30B, 30C, etc.The amount of protamine used can be chosen based on the probable amountsof heparin that exist in the blood sample. Thus, the cartridges 10 ofthis disclosure can be made available for a broad spectrum of surgicalheparin levels. For example, when a patient is known to have a possibleheparin level in his blood of between about 3 units per milliliter (ml)and 5 units per ml, in order to determine the precise amount ofprotamine that will be needed to neutralize the heparin in thatpatient's blood, the range of protamine placed into the conduits 30A,30B, 30C, etc. may extend from less than about 3 units per ml to morethan about 5 units per ml, with each conduit receiving a differentamount within that range. Under such a testing strategy, thefluid-receiving test chamber 32A, 32B, 32C, etc. in which clotting isfirst observed is that test chamber in which the amount of protamine isclosest to the amount of heparin activity in the blood that is beingcirculated.

With the above general explanations of exemplary systems includingmachines, cartridges and methods of use, FIGS. 15-16B schematicallyillustrate a further embodiment of a cartridge 110 and select componentsof a machine or device 100 in which the cartridge 110 can be used. Themachine 100 and cartridge 110 can configured similarly and used as asystem as described with respect to the embodiments above except asexplicitly stated. In this embodiment, the cartridge 110 includes aplurality fluid-receiving test chambers 132 (e.g., six, only a few ofwhich are referenced), each including a guide post 148 having a threadedsurface 135 that corresponds to at least one thread 147 of the magneticwasher 146, which is threadably engaged with the guide post 148. In oneembodiment, the threaded surface 135 includes threads oriented at anangle less than 45 degrees. As will be understood, the at least onethread 147 of the magnetic washer 146 will be correspondingly oriented.In some embodiments, the threaded surface 135 includes threads orientedat an angle in the range of 10 to 30 degrees. Therefore, absent externalrestrictive forces such as a clot, the magnetic washer 146 can berotated about the guide post 148 to translate the magnetic washer 146 upand down the guide post 148. The machine or device 100, which receivesthe cartridge 110, includes an actuating magnet 170 that is configuredto rotate about its center axis A as to correspondingly rotate themagnetic washer 146 either up or down the guide post 148 for a varietyof purposes. In an alternate embodiment, the actuating magnet 170 is anelectromagnet and the polarity of the electromagnet changes as thecurrent reverses direction every half cycle (AC voltage or currentsource) to apply bi-directional forces to the magnetic washer. Othertypes of actuating magnets are envisioned. The actuating magnet 170 canbe a permanent, horseshoe magnet or can be any other magnet that canalternatingly change its poles (N, S) or the position of its poles toapply magnetic force on the poles (N, S) of the magnetic washer 146 intwo directions along the guide post 148. The washer 146 can be moved upand down the guide post 148 to measure the viscosity change in a fluidsample for clotting. The distance the washer 146 moves along the guidepost 148 can be measured by a proximity sensor (not shown). The positiondetector in one embodiment is a radio frequency detector. Radiofrequency detectors sense the position of the washer 146 by sensing thechanges in the magnetic field surrounding the detection coil of theradio frequency detector that are caused by the presence of the washer146. Radio frequency detectors have sensitivity to ferromagnetic andother metallic materials and resistance to effects caused by otherelements of the device, such as the fluid. It should be understood,however, that other types of position detectors are also possible. Forexample, in another embodiment, the position detector is a Hall effectsensor and its associated circuitry, as generally described in U.S. Pat.No. 7,775,976 (the entirety of which is incorporated by reference) atcolumn 16, line 15 to column 17, line 5. Alternatively, the rotation ofthe washer 146 can be measured by a rotation or angle sensor (notshown). Clot formation is detected by the cessation of vertical washer146 movement (i.e. rotation) with respect to the guide post 148 ifsensed by a vertical position sensor or the cessation of the washerrotation with respect to the guide post 148 if sensed by a rotation orangle sensor.

In addition, the washer 146 can be moved in either direction along theguide post 148 after clot formation to assess elastic properties of theclot or firmness of a formed clot C as schematically depicted in FIGS.17A-17C (a non-clotted portion of the fluid sample is not shown for easeof illustration). In this embodiment, the stress force in thestrain-stress elasticity measurement is again controlled via theactuating magnet 170. In this way, the strain (compression orstretching) of the clot C can be controlled. Although the initiallocation of the washer 146 at the time of clot formation is notcontrolled, the distance the washer 146 can be moved up or down can becontrolled with the actuating magnet 170. Therefore, strain and stressforces on the clot C can be controlled in the system and the elasticityof the clot C can be reproducibly measured. In the case where the clot Cis formed under (FIG. 17A) or on top (FIG. 17B) of the washer 146, forcecan be applied to the washer 146 by orienting the poles (N, S) of theactuating magnet 170 accordingly to compress the clot C either againstthe floor or ceiling of the test chamber 132, respectively. If the clotC forms within the washer 146, the washer 146 can be pulled eitherupward or downward (FIG. 17C) along the guide post 148 with theactuating magnet 170 to apply a stretching force within the clot C. Bothcompression and stretch forces can be assessed to determine elasticproperties of the clot C.

Referring now also to FIGS. 18A-19B, which schematically illustrate onerepresentative test chamber 232 which can be incorporated into acartridge for use with a machine or device 200 (partially shown). Thecartridge (not shown) and the machine 200 can be configured similar toand operate as described with respect to the cartridges and machinesdisclosed above except as explicitly stated. As with prior embodiments,the cartridge includes a plurality fluid-receiving test chambers 232,each having a guide post or vane 248 and a magnetic washer or bar magnet246 having an aperture 247 through which the guide post 248 is inserted.The bar magnet 246 can have a length that is substantially the same asan internal diameter of the fluid-receiving test chamber 232. Only onefluid-receiving test chamber 232 is illustrated, however, it will beunderstood that the other fluid-receiving test chambers of a cartridgecan optionally be similarly configured so that all test chambers areidentical. The bar magnet 246 is configured to slide up and down theguide post 248 as controlled by an actuating magnet 270 provided as partof the machine or device 200 which can otherwise be of the type machinesdisclosed above with respect to prior embodiments. When the poles (N, S)of the actuating magnet 270 and the bar magnet 246 are similarlyaligned, the bar magnet 246 slides down the guide post 248 in adirection away from the actuating magnet 270 (FIG. 19A). When the poles(N, S) of the actuating magnet 270 and the bar magnet 246 are oppositelyaligned, the magnet force is such that the bar magnet 246 will generallyslide upward and will be drawn toward the actuating magnet 270 (FIG.19B). As indicated above, changes in the fluid viscosity of the fluidsample within the test chamber 232 may restrict movement of the barmagnet 246, thus indicating the formation of a clot. In one embodiment,the actuating magnet 270 is a permanent magnet that is a horseshoemagnet, which is configured in the machine 200 to rotate about itscenter axis A. The distance the bar magnet 246 moves along the guidepost 248 can be measured by a proximity sensor (not shown, see also theabove disclosure with respect to prior embodiments). Clot formation isdetected by the cessation of vertical movement of the bar magnet 246with respect to the vane 248. To prevent the bar magnet 246 fromrotating about the vane 248, the cartridge 210 can optionally include aplurality of rails 211 or the like positioned within the chamber 232. Inone example, the rails 211 extend along a height of the chamber 232 ateach of four corners of the bar magnet 246. Other ways of restrictingrotational movement of the bar magnet 246 are envisioned.

Elastic properties of a formed clot (not shown) can be assessed insimilar ways to that disclosed above with respect to the embodiment ofFIG. 15-17C by either moving the washer 246 either up or down along theguide post 248 to place compressive or stretching forces on the clot andfurther measuring a position of the washer 246 with the proximity sensor(not shown).

Although the present disclosure has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges can be made in form and detail without departing from the spiritand scope of the present disclosure.

What is claimed is:
 1. A method of analyzing a fluid sample; the methodcomprising the steps of: providing a cartridge including a chamberhaving a post and a magnetic washer engaged with the post; and anactuating magnet positioned proximate the chamber; moving the magneticwasher along the post in a first direction with the actuating magnet;and moving the magnetic washer along the post in a second direction withthe actuating magnet.
 2. The method of claim 1, wherein the magneticwasher is threadably connected to the post.
 3. The method of claim 1,wherein the fluid sample is human blood.
 4. The method of claim 1,wherein the magnetic washer is a bar magnet.
 5. The method of claim 1,further comprising the step of repeating the steps of moving themagnetic washer along the post in the first and second directions untilchanges in the viscosity of the fluid sample restrict further movementof the magnetic washer.
 6. The method of claim 5, further comprising thestep of identifying a clot in the fluid sample and then assessingelastic properties of the clot.
 7. The method of claim 6, wherein theelastic properties of the clot are assessed by applying a compressiveforce on the clot by moving the magnetic washer in a direction of theclot.
 8. The method of claim 7, wherein the direction is downward. 9.The method of claim 6, wherein the washer is positioned within the clot;the method further comprising the step of applying strain in the clot bymoving the magnetic washer with the actuating magnet to stretch theclot.
 10. The method of claim 1, wherein the actuating magnet is anelectromagnet.
 11. The method of claim 1, wherein the steps of movingthe magnetic washer along the post in the first direction and moving themagnetic washer along the post in the second direction each includeactivating the actuating magnet.
 12. The method of claim 11, wherein thestep of activating the actuating magnet includes arranging poles of theactuating magnet with poles of the magnetic washer.
 13. A method ofanalyzing a fluid sample; the method comprising the steps of: providinga cartridge including a chamber having a post and a bar magnet engagedwith the post, the bar magnet including N pole and a S pole; and anactuating magnet positioned proximate the chamber, the actuating magnethaving a N pole and a S pole; moving the bar magnet along the post in afirst direction away from the actuating magnet with the actuating magnetby aligning the N pole of the bar magnet with the N pole of theactuating magnet; and moving the bar magnet along the post in a seconddirection toward the actuating magnet with the actuating magnet byaligning the N pole of the bar magnet with the S pole of the actuatingmagnet.
 14. The method of claim 13, wherein the actuating magnet is apermanent horseshoe magnet.
 15. The method of claim 13, wherein theactuating magnet is an electromagnet.
 16. The method of claim 13,wherein the post is threaded.
 17. The method of claim 13, furthercomprising the step of compressing a clot formed in the fluid sampleagainst one of a floor of the chamber and a ceiling of the chamber bymoving the bar magnet.
 18. The method of claim 13, further comprisingthe step of stretching a clot formed in the fluid sample by moving thebar magnet.
 19. The method of claim 13, wherein the fluid sample ishuman blood.